Hello all, got a small issue with the Mark surging. This past week end I did some upgrades to my intake and fuel system. I added a 255 intank fuel pump, 21lb injectors, and a new reproduction cobra gt40 upper and lower intake manifold. Everything bolted up nicely and the car made a 90 min trip after all of the work was done without breakin down on me. The only problem I am now experiencing is the engine surges while at idle and acts like it wants to stall. I'm guessing its a vacum like somewhere as I now don't have the EGR plate anymore. On the stock EGR there where two vaccum lines; one on each side of the plate just behind the throttle body. On the new intake manifold these lines are eliminated so I just blocked off the lines and sat them aside. This is the only thig I can think of that would be the obvious but I would think ford would of thought of this and came up with a solution. I noticed a couple of guys have this same intake and was wondering if anyone could reccomend any lines I should check to try and solve this problem.

you still have the speed density stuff or did you switch it to mass air?

I know that in a lightning, if you put in bigger injectors with the stock computer it surges like a bitch. switching the chip and or going to mass air from a stang eliminates this issue.

also, a dirty o2 sensor will cause surging in a speed density car, even if you don't get a code.

another thing to try, unhook your battery for the night to kill the computer. this helps sometimes.

i dont have a lot of experience with lincolns yet but i DO know quite a bit about mustangs and gen 1 lightnings.

Yeah I am still SD. I reset the computer after all mods where complete so I don't think that's the problem.

I believe that surging is normally from a lean or rich codition. I know that with my grand prix, I put in 42lb injectors and I had to reprogram the pcm for the new injectors otherwise it would run insanely rich.

I have found that every time I had a surging problem, It was caused by a vacume leak.

Put back the 19# injectors.